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- Moreau, D., et al.
(författare)
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A two-time-scale dynamic-model approach for magnetic and kinetic profile control in advanced tokamak scenarios on JET
- 2008
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 48:10
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Tidskriftsartikel (refereegranskat)abstract
- Real-time simultaneous control of several radially distributed magnetic and kinetic plasma parameters is being investigated on JET, in view of developing integrated control of advanced tokamak scenarios. This paper describes the new model-based profile controller which has been implemented during the 2006-2007 experimental campaigns. The controller aims to use the combination of heating and current drive (H&CD) systems-and optionally the poloidal field (PF) system-in an optimal way to regulate the evolution of plasma parameter profiles such as the safety factor, q(x), and gyro-normalized temperature gradient,. rho*(Te)(x). In the first part of the paper, a technique for the experimental identification of a minimal dynamic plasma model is described, taking into account the physical structure and couplings of the transport equations, but making no quantitative assumptions on the transport coefficients or on their dependences. To cope with the high dimensionality of the state space and the large ratio between the time scales involved, the model identification procedure and the controller design both make use of the theory of singularly perturbed systems by means of a two-time-scale approximation. The second part of the paper provides the theoretical basis for the controller design. The profile controller is articulated around two composite feedback loops operating on the magnetic and kinetic time scales, respectively, and supplemented by a feedforward compensation of density variations. For any chosen set of target profiles, the closest self-consistent state achievable with the available actuators is uniquely defined. It is reached, with no steady state offset, through a near-optimal
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- Von Lensa, W., et al.
(författare)
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Red-impact : A European research programme to assess the impact of partitioning and transmutation on final nuclear waste disposal
- 2008
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Ingår i: Int. Congr. Adv. Nucl. Power Plants - ICAPP, "Nucl. Renaiss. Work". - 9781604238716 ; , s. 2564-2573
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Konferensbidrag (refereegranskat)abstract
- It is the objective of the EU-funded 'Red-Impact' project to analyse the impact of partitioning, transmutation and waste reduction technologies on the final nuclear waste disposal. The partnership of 25 organisations is originating from European nuclear industry, waste agencies, research centres and universities. The system studies focus on a realistic evolution of P&T technologies and advanced fuel cycles which can be deployed incrementally on an industrial scale as well as on future developments such as reactors of the third and fourth generation (Gen III & Gen IV) and Accelerator Driven Systems (ADS). A comprehensive inventory of all existing and foreseen nuclear fuel cycle facilities in Europe has been performed including a review on worldwide ongoing R&D programs on P&T. Thus, it was possible to select a set of three so-called "industrial scenarios", taking into account industrial feasibility of alternate strategies leading to increased actiniae burning and reduced actinide generation based on direct disposal (reference case) or MOXfuel for LWR and plutonium recycle in Sodium Fast Reactors (SFR). R&D needs for the development of processes and technologies have also been addressed. In addition, three 'innovative scenarios ' have been identified allowing multi-recycling of plutonium and minor actinides in SFR and Accelerator-Driven Systems (ADS) as well as GANEX or COEXprocess and PYRO reprocessing technologies. Waste streams have been calculated for all of these scenarios including the transition from the present situation towards new fuel cycle options. These data provide the input to specific analyses on the impact on geological disposal in different host formations such as granite, clay and salt. The results show that advanced fuel cycles influence the required size of the geological repository in case of disposal in clay, salt or hard rock formations. Recycling of all the actinides results in a reduction of the necessary gallery length (depending on geology and design) at least by a factor 3. If additionally cesium and strontium are extracted from the high-level waste for separate decay, the reduction factor will become 10 or more. In the frame of the project, the feasibility and the impact of the Cs or Sr separated management were not assessed or evaluated. Transmutation of the actinides fast neutron spectrum reactors (FR or ADS) results in a limited reduction of the maximum dose because the dose is essentially due to long-lived fission and activation products. On the other hand, reprocessing the spent fuel decreases the maximum dose at the storage with a factor 5 because a considerable fraction of the iodine is separated from the high level waste during reprocessing. The radiotoxicity in the high level waste or spent fuel as well as human intrusion doses after 500 years are drastically reduced by the transmutation of the actinides. Evaluating actinide minimization systems and industrialised P&T in general requires an assessment of relevant nuclear fuel cycles especially with regard to the economic, environmental and societal advantages/disadvantages (i.e. the sustainability of the fuel cycles). Thus, a set of indicators has been derived for each of these areas. The results are analysed using the multi-criterion analysis approach which allows the importance of each of the indicators to be specified.
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- Westlén, Daniel, et al.
(författare)
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Impact of P&T on geological repositories an overview of the euratom red impact project
- 2007
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Ingår i: GLOBAL 2007. - 0894480553 - 9780894480553 ; , s. 772-781
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Konferensbidrag (refereegranskat)abstract
- The European Commission project Red Impact is in a state of conclusion after three years. Within the project, the consequences of P&T on, mainly, geological disposal have been investigated. Six scenarios have been developed, including three considered to be deployable today, and three more advanced scenarios including P&T in different ways. The scenarios all have different strengths and weaknesses, which are discussed in the present paper.
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